Propeller pitch change mechanism



Av i/e v o? 2 Sheets-Sheet 1 H D BURKHALTER, JR

PROPELLER PITCH CHANGE MECHANISM Filed Feb. 27, 1945 MR4) 0 BQEK er 2 V Dec. 26,. 1944.

1944- H. D'. BURKHALTER, JR

PROPELLER PITCH CHANGE MECHANISM Filed Feb. 27, 1943 Y 2 Sheets$heet 2 Patented 26, v i

UNITED STATES PATENT OFFICE 2,3 5,616 PRQPELLER rrrcn CHANGE MECIIANISMI Barry D. Burkhalter, Jr., Bowling Green, Ohio Application February 27, 1943, Serial-No. 477,408 8 Claims. (c1. I'm-163 (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G, 757) The invention described herein may be manu diagram illustrating automatic operation of the factured and used by or for the Government for system. governmental purposes, without the payment, t Like numerals refer to like parts throughout me of any royalty thereon. a the several views.

This invention relates to adjustable 'pitch pro- Construction pellers for aircraft, and particularly to a mechanism for controllingfthe pitch'of the blades.

The idea of employing the power unit which rotates the propeller 'to additionally effect changes in the'pitchof the blades is broadly old, 10 but heretofore the, mechanism for accomplish-' in this re'sulthas uall o i g sea so g z i fi g g gf gggi g spokes 24, the outer ends of which carry the a brake to one or the other of two .members ro- F a p0rtl9nwmFh support the beartated the propeller blades for increase or decrease housmgs 28 wlthm whlch the blades 30 are of their pitch- I I r 35 51 1 control driving ear 32 is preferably ggg gg gg i gi fi gsfi gg gg az jfi integral with or otherwise permanently securedv between the R. P. of the propeller hub and the tofihe rear end of the. hub A pltch contrim R. P. M. at which the blades rotate'about their dnven freely mtatab-Ie on the hub axs is y a large number of speed reduc may preferably be of substantially the same size mg gears are us'uauy required as the pitch control driving gear, and should It is therefore an'obie'ct ofthis invention to 'h-aveothe same number of The dnven Provide a. gear mechanism of few arts and bpltch coptrol gear has a elatwely long hub small dimensions which wnposs'essth p 1 l at the forward end of which are formed a series 6 re 3' W y of arms 38.

Mounted on the shaft ll] of an aircraft engine I2 is the'propeller hub Hi. The manner of securing the hub to the shaft may be conventional, as by the splined portion I6, conical collars '18 and 20 and the nut 22.

At the forward end, the hub [4 has radial great speed reducing capacity required in tran's- A planetary reaction gear 40 is integral with laitmg the lush prfpener hub Speed the 510w or otherwise permanently secured to the hub l4. pitch change mtatmn of the A driven speed reducing gear 42,'freely rotatable Anotfher object of the mventlon 15.190 Pmvide on the hub I4, is preferably, although not neces- -F Y simple control means for makingthe 3o sarily, of the same diameter' and number of pitc ma- ES l m l teeth as the reaction gear 4!). The driven speed other l n Q W111 become reducing gear 42 has a long hub 44, on the for- Parem? from consldemmqn the following ward. end of which there is formed a bevel gear flescriptionifaken in h draw 46. Mating bevel gears 48 are secured, one on mgs, Wherem: r 1 the inner end of each b1ade'30, all gears 48 be- 1 is a longitudinal axial section taken at in t t h ith the gear 46.

thmllgh vrepeller mecnamsm The arms 38 of the planet pinion carrier 39 made m my inventmn'! a Portion of each carry a stud 50 upon which there is freely the s ti and their Operating mechanism being {rotatable an elongated planet pinion 5|, which Shown fi l has a face wide enough to engage the teeth of 2 a real end-mew Seen from line both gears 40 and 42. However, if the difference 22 looking at Fig. 1- from thewlefifh between the numbers of teeth in gears 40 and a! Fig. 3 is a transverse section through the sevis less than thenumber of g 3a, t t th of eral Solenoid p e clutches and some of m one only of the pinions may extend straight across gearing operated thereby, the section being taken as n t i i 5|, hil the other pinions a -3 0 a will have the teeth of one half of the pinion a Fis- Q i a tr r e section throughgnother 'at 52 misaligned with the teeth of the other h gear-set, the section being taken at 4-4 of Fig. 1. v 54. Such an elongated pinion may preferably b Fig. -5 is a schematic illustration and wiring made by cutting portions '52 and 54 separate and joining them together. by enemy parallel rivets or similar means with; theteeth or ert s2 and 42 are made to difler by as many teeth as and 42 and there are three arms 38. It is therefore necessary to make'tw'o of the three elongated pinions as at 52, 54, and the other as at 5|. If, however, the number of teeth in gears 48 there are pinio'n studs 58 on the carrier, then all of theplanet pinions will be single as at 5|, the teeth extending across both gears 48 and 42. 'Ihe studs 58 are so positioned as to. maintain constant mesh between' the pinions SI, .52, 54 and the gears 48 and 42. The hub, the arms 38 and the studs 58 may collectively be referred to as the planet pinion carrier, and may be broadly designated by the numeral 39; A gear cover 56 encases the carrier '39, thespeed reducing gears 48 and 42, and the pinions 5|, 52 and 54,

Non-rotatably mounted on the nose of the en glne I2by screws 58 is the control gear and control pinion housing 68. The driving control gears 32 and driven' control gear 34 havepreviouslybeen described. Circumferentially spaced d countershafts 62 near their ends are supported in the housingi68, and the driving and driven control pinions designated 64 and -88 respectively are rotatable on these countershaits. I

Control pinion 84 has an externally splined sidered within thepurview of the invention to employ fluid actuated hydraulic -pistons for the same purpose.

It is here noted that the control gearing, con

sisting of gears 32 and 34, and pairs of pinions I 64 and 65, is not, like the speed reducing gearing, of the planetary type, but consists merely of several stationary countershafts with pairs of pinions through which the driving control gear 32' rotates the driven control gear 34-at asynchronous speed, or at a greater or less speed, depending on which control unit is brought into.

' play.

hub- 68 extending forwardly while control pinion 66 has an internally splined drum I8 extending rearwardly over the hub 88. Antiiriction bearings 12 in the hub 68 rotatably support the gear 84, while roller'bearings I4 rotatably supportthe gear 86 on theoutside or the hub 68, A stack I8 of clutch discs, one toothed externally I to fit the internal splines in the druni18,and

the next toothed internally to fit the external splines in the hub 68, are provided for the purpose of drivably connecting the pinion 64 to the pinion 86. Solenoid coils I8 are circumterentially spaced in the housing 68, one for each pair 01' control pinions Gland 68, for the purpose of compacting the discs "to eflect driving connectionbetween the two-pinions.

An enlarged portion 88 on each'shaft 82 serves as a core for the solenoid. A flange 82 is fast on each shaft, whereby, when the solenoid coil is energized, the flange 82 is drawn up, the

I clutch discs 18' are compacted, and the'pinions 64 and 66 are drivably engaged. An expansion spring actson the core 88 to disengage the clutch when the coil I8 is deenergized. The con-1 trol pinion and solenoid clutch assembly, conf sisting of parts .d'esigna'ted-bythe even numerals 7 between 62 and 84, inclusive, may conveniently be referred to as control units, and be broadly designated by the numeral 85, and sincethere are three assemblies 85 which 'difler in a'small particular, i. e. a difference of one toothas between pinions 84 and 68, the several control units may preferably beiurther distinguished as the pitch increasing control unit 85A, the pitch locking control unit 85B, and the pitch decreasing control unit 850. 7

While the clutches 16 are here shown as actuated by an electro-magnetic means,;it' is con- 76 and'the pitch increasing control unit 85A will be disengaged whenever either Let gears 32, 34 end 42' i Let pinion- 84 and as driven :by' an engine 88 is arranged to move a grounded contact 98 upward to engage the contact 92 to increase the pitch when the engine overspeeds, and, downward to engage the contact 94 to decrease the pitch when theengine under Sp eds. 1 Engagement of contacts 98 and 92 energizes relay- 96, which closes the switch 98 and opens.

the switch I88, whereby current from ,thelsource I82 drivablyengages the control pinions of control unit 85A and drivably disengages the pinion of control unit 853. t

' On the other hand, engagementoi contacts- 98 and 94 energizes relay I84, which closes'the switch I88 and opens the switch I88 whereby current from the source I82 drivably engages the pinions of control unit 850 and drivably disengages the pinions of control unit 85B. It will be observed that control unit 853 always becomes unit 85A or unit 850 becomes engaged. I V

s Operation The operation of the mechanism hereinbefore described may more readily .be understood 'by specifying the hu hrleer of teeth on each or the I 7 several control gears and pinions and on each of theseveral speed-reducing gears and pinions. 7

Accordingly, each have teeth. Let gear 48 have 59' teeth. Let pinion 64 and 86 mass have respectively.

s in ass have 40 e 40 teeth respectively.

Let pinion s4 and in ascet 'eoeha 39 teeth a respectively.

L t pinions 52 and 54 each have 2 teeth.

'As long as the engine 88 ision speed," the governor 86 will hold the contact 98 out of engagement: withboth 92 and. 94, whereby the switch. I8l'will remainclosed and the pitch lock! lng control unit 85B will be operative.

If the" engine overspeeds, the contact 98 will a engage 92, whereby the relay l6 simultaneously closes the. switch 98 and opens the switch'.llll,

operative to increase the propeller pitch.

It the engine /underspeeds, the contact. will engage 54, whereby the relaylll simultaneously closes the switch I88 and-opens the switch I88, and the pitch decreasing'control unit 856 will be operative 'rp decrease the propeller-pitch.

jfiince the pitch-locking control unit 853 has an equal number or'teeth on pinions 84 and 68,

the driving gear 32 rotate the driven gear 34 at one to'one ratio so that the planet pinion carrier 39 will also rotate at one to one ratio whereby. the'pinions BI, 52, and I54 are prevented by gear 48 from rotating and the bevel gear 48 In the schematic view, Fig. 5, a governor 86,

40 and 41 teeth.

must rotate at propeller hub speed. .As long,

therefore, as control unit 8531s operative, no

pitch changecan take place.

Since the pitch increasing control unit 85A has 40 teeth on the'pinion 64 and 41 teeth on the pinion 66, each rotation of the driving control gear 32 will advance thedriven control gear 34 with respect to'the propellerhub l4 through 340 turn, and since the gear 40 has 59 teeth and the gear 42 has 60' teeth, one turn of the carrier 39 with respect to'the. hub I4 will rotate the gear 42 through tio' turn with respect to the hub I4. The overall ratio between the driv- -ing control gear-32 and the driven speed reducing gear 42 isio co= ,4oo, that is, with the pitch increasing control unit 85A operative, each propeller revolution will rotate a blade 30 through /2400 revolution -in the pitch increasing direction as indicatedby the arrow I68.

Since the pitch decreasing control unit 85B has 40 teeth on the pinion 66, each rotation of the driving control gear 32 will retard the driven control gear 34 with respect to the hub |4-an amount 'equal to /10. turn, and since the ratio through the speed reducing gear-set is 1 to ,4), the overall ratio is lto %o= /2ioo, that is with the pitch decreasing control unit 85B operative, each propeller revolution will rotate a blade 30'through fierce revolution in the pitch decreasing direction, i. e., opposite to the arrow I08.

The rate of pitch change may conveniently be ascertained by means of the following equation:

ed =degrees per second pitch change wherein,

c=number of teeth on speed-reducing reaction gear 46,

d=number of teeth on speed-reducing driven gear 42,

e=number of teeth on control pinion 64",

j =number of teeth on control pinion 66, and

T=revolutions, of propeller per second.

Substituing tor c, d, c, and f in the equation, the numbers of teeth hereinbefore assignedto gears-40 and 42 and pinions 64 and 66, respectively, and making r=20 ropeller revolutions per second, the pitch change rate will be 3 degrees per second. r 1,

The above equation is'applic'able where there is a difierence of one, two or more teeth between gears 40 and 42, and one, two or more teeth between pinions 6'4 and 66. Where the difierence is only one tooth in each case, the equation -may be further simplified to read %=degrees per second pitch change wherein the values are the same as-irnEquation 1. I

From the foregoing, it will be understood that the mechanism described will operate to positively lock against pitch change; to increase pitch at 3 degrees per second; or decrease the pitch at 3 degrees per second, depending on which of the three control units, 85A, 853 or 850 is actuated. A pitch change rate or 6 degrees per second could be readily had by merely makin a difference of two teethbetweengears 40 and 42 instead of 1 tooth as used in the example. A similar result may be. had by providing equal numbers of teeth on speed-reducing gears 40 and 42, and making the elongated pinions all in two parts as at 52 and 54, and having one or more teeth diiiference between parts 52 and 54.

Instead of employing a pitch-locking control unit 853, other means may be employed -for locking the blade against pitch change and the other comprising a, driving control gear fast on said hub, a driven control gear, having the same number of teeth as said driving control gear,

freely rotatable on said hub, and several control units, one control unit comprising a countershaft,a driving pinion rotatable on said countershaft in mesh with said drivin control gear, a

u driven pinion rotatable on said countershaft in mesh with said driven control gear, the driven pinion having one more tooth. than the driving pinion, a second control unit comprising a countershaft, a driving pinion rotatable onsaid co untershaft in mesh with said driving control gear,

a driven pinion rotatable on said countershaft in mesh with said driven control gear, the driving and the driven pinions having the same number of teeth, a third control unit comprising a countershaft, a, driving pinion rotatable on said countershaft in meshwith said driving control gear,

a driven pinion rotatable on said countershaft in mesh with said driven control gear, the drive ing pinion having one more tooth than the driven pinion, the three control units each having a clutch for joinin the driving and driven pinions in driving relation, and electromagnetic means for engaging the clutches, and a planetary speedreducing gear-set in said speed-reducing gear housingcomprising a reaction gear fast on said hub, a driven speed-reducing gear freely, rotattable on said hub, said reaction gear having one less tooth than said driven speed-reducing gear, a planet pinion carrier fast on said driven control gear, and one or more elongated planet pinions yrotatable on said carrier, and revolved thereby about and in mesh with both said reac-' tion and driven speed-reducing gears, a driving bevel gear fast on said driven speed-reducing gear and a driven bevel gear on each propeller blade in mesh. with the driving bevel gear.

.2. A variable pitch propeller mechanism for an aircraft engine comprising a propeller hub, blades ,having their inner ends rotatable in said hub, bearings carried by said hub for rotatably supporting said blades, a'control-gear support non-"rotatably attached to said engine, a'control gear-set comprising a drivin control gear fast on said "hub, a driven control gear, having the same number of teeth as said driving control gear, freely rotatable on said hub, and several control units, one control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear, a driven pinion rotatable on said counter shaft-in mesh with said driven control gear, the

driven pinion having one more tooth than the driving pinion, a second control unit comprising i a countershaft, a driving pinion rotatable on said countershaft in mesh withsaid driving control gear, a driven pinion rotatable on said counter shaft in mesh with said driven' control gear, the driving and the driven pinions having. the same number of teeth, athird control u'nitccmprising a countershaft, a driving pinion rotatable on said countershaft in mesh with saiddriving control gear, a driven pinion rotatable on said countershaft in mesh with said driven control gear, the driving pinion having one more tooth than the driven pinion, thethree countershafts ends rotatable in said hub, bearings carried by said hub for rotatably-supporting said blades, 0. control gear-set comprising a driving control gear fast on said hub. a driven control gear, having the same number of teeth as said driving control gear, freely rotatable on said hub, and several control units, one control unit comprising a counbeing carried by said support and the three control units each having a clutch for joining the driving and driven pinions in driving relation and electromagnetic means .for engaging the clutches, and a planetary-speed-reducinggearset comprising a reaction gear fast on said hub,

a driven speed-reducing gear freely rotatable on said hub, said. reaction gear having 'one' less tooth than said driven, speed-reducing gear, a'

\ porting said blades, a control-gear support non rotatably attached to saidengine, a control gearset comprising a driving control gear fast" on said hub, a driven control gear, having the same num-. ber of teeth as said driving control gear, freely rotatable on said hub, and several control units,

one controltunit comprising a countershaft, a driving pinionrotatable on said countershaft in \mesh with said driving control gear, a driven pintershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear,

a driven pinion rotatable on said countershaft in mesh with said driven control gear, the driven pinion having one more tooth han e in pinion, a second control unit comprising a countershaft, a-driving pinion rotatable on said countershaftin mesh with said driving control gear,

a driven pinion rotatable .on said countershaft in mesh with said driven control gear, the driving and the driven pinions having the same number of teeth, a third control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving'control gear, a driven'pinion rotatable on said'countershaft in mesh with said driven control gear, the driving pinion having one more tooth than the driven pinion, the three control units having their axes fixed and parallel to the hub axis, a clutch in each unit for joining the driving and driven pinions in driving relation, and power means for engag- [ing the clutches, and a planetary speed-reducing gear-set comprising a reaction gear'fast on said hub, a driven speed-reducinggear freely rotatable on said hub, said reaction gear having one less tooth than said driven speed-reducing gear,

a planet pinion-carrier fast on said drivencontrol gear, and one or more "elongated planet pinions rotatable on said carrier and revolved thereby about and in mesh with both said reaction and driven speed-reducing gearsyand power transion rotatable on said countershaft in mesh with said driven control gear, the driven pinion having one more tooth than the driving pinion, a second control unit comprising a countershaft, a

- driving pinion rotatable on said countershaft .in

'mesh with said driving control gear, a driven pinion rotatableon said countershaft in mesh with said driven control gear,-.the driving and the driven pinions having the same number of teeth, a third control unit comprising a countershaft, a driving pinion rotatable on'said countershaft in mitting means rotatably connecting the speed-reducing driven gear to the propeller blades.

' 5. A variable itch'propellerv mechanism comprising a propeller hub, blades having their inner, endsrotatable in said hub, bearings carriedvb said hub for rotatably supporting said blades, a control gear-set comprising a driving control gear fast on said hub, a driven control gear, having the same number of teeth as said driving control gear, 3 freely rotatable on said hub, and several control mesh with. saiddriving control gear, a driven pin ion rotatable on said countershaft in mesh with said driven control gear, the driving pinion hav-' ing one more toothithan the driven pinion, the

three countershafts being carried by said su port and the three control units each having a clutch for joining the driving and driven pinions in driving relation, and power means for engaging the clutches, and a planetary speed reducing gear- 'set comprising a reaction gear fast on said hub, a driven'speed reducing gear freely rotatable on said hub, said reaction gear having one less tooth .than said driven speed-reducing. gear, a planet pinion carrier fast on said driven control gear,

and one or more elongated planet pinions rotatable on said carrier and revolved thereby about "and in mesh with both said reaction ,and driven speed-reducing gears, and power transmitting means connecting thesaid speed-reducing driven units with axes in fixed positions parallel to the hub axis, one control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear, a driven pinion rotatable on said countershaft-in mesh with said driven control gear, the driven pinion having one more tooth than the driving pinion, a second control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear,

a driven pinion rotatable on said countershaft in mesh with said driven control gear, the driving and the driven pinions having the same number .of teeth, a third control unit comprising a com tershaft, a driving-pinion rotatable on said countershaftin mesh with said driving control gear,

a driven pinion rotatable on said countershaft in mesh with said driven control gear, the driving pinion having'one more tooth than the drivenpinion, a clutch in each of the three control units 'for-ioinin'g the driving and driven pinions in gear to the propeller blades .to rotate said blades.

4. A variable pitch propeller mechanism comdriving relation, and means for selectively enga ing the clutches, and a planetary speed-reducing gear-setcomprising a reaction gear fast on said -hub, a driven speed-reducing gear freely rotat-' able on 'said hub, said reaction gear having one prising a propeller hub, blades having their inner less tooth than said driven speed-reducing gear,

a planet pinion carrier fast on said driven control gear, and one or more elongated planet pinions rotatable on said carrier and revolved thereby about and in mesh with both said reaction and driven speed-reducing gears, and means drivably connecting the driven speed-reducing gear to the propeller blades.

6. A variable pitch propeller mechanisrncom-I prising a propeller hub, blades having their inner ends rotatable in said hub, bearings carried by said hub forrotatably supporting said blades,-

a control gear-set comprising a driving control gear fast on said hub, a driven control gear, having the same number of teeth as said driving con- -trol gear, freely ,rotatable on said hub, and several control units with axes in fixed positions parallel to the hub axis, one control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear, a driven pinion rotatable on said countershaft in mesh with said driven control of the two control units for joining the driving/'30 and driven pinions in driving relation, and means for selectively engaging the clutches, and a planetary speed-reducing gear-set comprising a reaction gear fast on said hub, a driven speedreducing gear freely rotatable on said hub. said reaction gear having one less tooth than said driven speed-reducing gear, a planet pinion carrier fast on said driven control gear, and on or more elongated planet pinions rotatable on said carrier and revolved thereby about and in mesh able on said counters heft inmesh with said driving control gear, a driven pinion rotatable on said countershaft in mesh with said driven control gear, one of the two pinions of each control unit having one more tooth than the other of the two, a clutch for each of the two control units for joining the driving and driven pinions in driving relation, and means for selectively engaging the clutches, and a planetary speedreducing gear-setcomprising a reaction gear concentrically secured on said hub for rotation therewith, a driven speed-reducing gear freely rotatable on said hub, said reaction gear havin one less tooththan said driven speed-reducing gear, a planet pinion carrier fast on said driven control gear, and one or more elongated planet pinions rotatable on said carrier and revolved thereby about and in mesh with both said reaction and driven speed-reducing gears and means drivably connecting the driven speed-reducing gear to the propeller blades.

8. A variable pitch propeller mechanism comprising a propeller hub, blades having their inner ends rotatable in said hub, bearings carried by said hub for rotatably supporting said blades, a control gear-set comprising a driving control gear fast on said hub, a driven control glean-having the same number of teeth as said driving control gear, freely rotatable on said hub, and two control units with axes in fixed positions parallel to the hub axis, each control unit comprising a countershaft, a driving pinion rotatable on said countershaft in mesh with said driving control gear, a. driven pinion rotatable on said countershaft in mesh with said driven control gear,

one of the two pinions of each control unit having more teeth than the other of the two, a clutch for each of the two control units for joining the driving and driven pinions in driving relation,

with both said reaction and driven speed-reduc- I ing the same number of teeth as said drivin control gear, freely rotatable'on said hub, and two control units with axes in fixed positions parallel to the hub axis, each control unit comprising a countershaft, a driving pinion rotatand means for selectively engaging the clutches, and a planetary speed-reducing gear-set comprising a reaction gear concentrically secured on said hub for rotation therewith, a driven speedreducing gear freely rotatable on said hub, said reaction gear having one less tooth than said driven speed-reducing gear, a planet pinion carrier fast on said driven control gear, and one or more elongated planetpinions rotatable on said carrier and revolved thereby about and in mesh with both said reaction and driven speedreducing'gears and means drivably connecting the driven speed-reducing gear to the propeller blades.

' HARRY D, BURKHALTER, JR. 

